The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board (PCB) attached to a disk drive base of the HDA. The head disk assembly includes at least one disk (such as a magnetic disk, magneto-optical disk, or optical disk), a spindle motor for rotating the disk, and a head stack assembly (HSA). The printed circuit board assembly includes electronics and firmware for controlling the rotation of the spindle motor and for controlling the position of the HSA, and for providing a data transfer channel between the disk drive and its host.
The spindle motor typically includes a rotor including one or more rotor magnets and a rotating hub on which disks mounted and clamped, and a stator. If more than one disk is mounted on the hub, the disks are typically separated by spacer rings that are mounted on the hub between the disks. Various coils of the stator are selectively energized to form an electromagnetic field that pulls/pushes on the rotor magnet(s), thereby rotating the hub. Rotation of the spindle motor hub results in rotation of the mounted disks.
The head stack assembly typically includes an actuator, at least one head gimbal assembly (HGA), and a flex cable assembly. During operation of the disk drive, the actuator must rotate to position the HGAs adjacent desired information tracks on the disk. The actuator includes a pivot bearing cartridge to facilitate such rotational positioning. One or more actuator arms extend from the actuator body. An actuator coil is supported by the actuator body opposite the actuator arms. The actuator coil is configured to interact with one or more fixed magnets in the HDA, typically a pair, to form a voice coil motor. The printed circuit board assembly provides and controls an electrical current that passes through the actuator coil and results in a torque being applied to the actuator. A crash stop is typically provided to limit rotation of the actuator in a given direction, and a latch is typically provided to prevent rotation of the actuator when the disk dive is not in use.
Each HGA includes a head for reading and writing data from and to the disk. In magnetic recording applications, the head typically includes an air bearing slider and a magnetic transducer that comprises a writer and a read element. The magnetic transducer's writer may be of a longitudinal or perpendicular design, and the read element of the magnetic transducer may be inductive or magnetoresistive. In optical and magneto-optical recording applications, the head may include a mirror and an objective lens for focusing laser light on to an adjacent disk surface. The microscopic spacing between the read or write transducer, and the surface of an adjacent rotating disk media during operation, is typically referred to as the so-called “flying height” of the head. The flying height is typically an important parameter upon which device performance depends, and so variation of the flying height in response to changes in operating and environmental conditions is typically undesirable.
The HGA includes a flexure that includes a tongue to which the slider is adhered. The adhesive cures after the slider is aligned within close proximity to the tongue. During this alignment, the adhesive can be in a liquid form and be compressed or otherwise distorted by the relative movement of the slider and the tongue. The tongue often includes stand-offs (e.g. having a known height equal to a flexure layer thickness) that the slider rests upon, so as to determine and maintain the spacing between the slider and the tongue. Control of this spacing can be desirable, for example, to ensure parallelism between the slider and the tongue, and/or to maintain a desirable vertical position of electrically conductive bonding pads on the slider relative to electrically conductive traces on the flexure. However, if some adhesive gets inadvertently displaced, for example during alignment due to the relative movement of the slider and the tongue, or because of other forces acting upon the adhesive (e.g. surface energy or gravity), so as to lie upon one or more of the stand-offs, then the parallelism and/or vertical position of the slider relative to the tongue can be disturbed. In that case, the pitch static attitude (PSA) and/or roll static attitude (RSA) of the slider can be affected, leading to a change in flying height during disk drive operation after assembly. If some adhesive often gets inadvertently displaced so as to lie upon on or more of the stand-offs during the manufacturing process, then flying height variation within a population of HGAs can be undesirably increased.
Thus, there is a need in the art for an improved flexure design that reduces the likelihood that the process by which the slider is bonded to the tongue will increase static attitude variation within a population of HGAs.